The biggest ever scientific study of near-death experiences shows that awareness can continue for a surprisingly long duration after the brain has shut down completely. The finding suggests that these experiences are more than just hallucinations — and that our definition of clinical death should probably be revised.

Near-death experiences (NDEs) and out-of-body experiences (OBEs) have long been documented. They're particularly common among people who have suffered a cardiac arrest (CA). First responders or physicians are told to make a declaration of death when, after a variable length of time, there's no cardiac output, no respirations, and the pupils have become fixed and dilated. But in those very early stages after a CA, when cerebral blood flow and electrical brain activity are impaired or null, some people experience a wide range of subjective phenomenon. Survivors talk about "seeing a tunnel," a "mystical being," "feelings of peace," a feeling of separation from their bodies, and awareness of things during the episode or event.

Life After 'Death'

Normally, these accounts are cast aside as being hallucinations or illusions, and that they're not really indicative of true conscious awareness. But to date, objective and scientific studies have been extremely limited. In an effort to correct this, the University of Southampton's Sam Parnia examined the broad range of mental experiences as they occurred around death-like states. And fascinatingly, he also tested the validity of conscious experiences by using objective markers to see if claims of awareness with OBEs actually meshed with real or hallucinatory events.

His findings show that these experiences are real and that they should be taken much more seriously, especially by scientists. And remarkably, he showed that a fraction of patients can experience real events for up to three minutes after brain activity has stopped — which was thought impossible — and that they could recall them accurately once they had been resuscitated.

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Parnia and his team studied 2,060 CA patients as part of the international AWARE (AWAreness during REsuscitation) study. Of them, 330 survived — of which 140 (or 42.4%) said they had experienced some kind of awareness while being resuscitated. Of the survivors, 39% were able to undergo structured interviews. Interestingly, most of them did not have any explicit recall of events, suggesting that more people have mental activity but then lose their memories after recovery (i.e. due to the effects of brain injury or sedatives).

Of those interviewed, 46% experienced a broad range of mental recollections that were incompatible with what we consider to be true NDEs, including fearful and persecutory experiences. Only 9% had experiences compatible with NDEs and a scant 2% exhibited full awareness compatible with OBE's with explicit recall of seeing and hearing events.

But that 2% is a very interesting 2% indeed. One case was validated and timed using auditory stimuli during CA. A release from the University of Southampton elaborates:

Dr Parnia concluded: "This is significant, since it has often been assumed that experiences in relation to death are likely hallucinations or illusions, occurring either before the heart stops or after the heart has been successfully restarted, but not an experience corresponding with 'real' events when the heart isn't beating. In this case, consciousness and awareness appeared to occur during a three-minute period when there was no heartbeat. This is paradoxical, since the brain typically ceases functioning within 20-30 seconds of the heart stopping and doesn't resume again until the heart has been restarted. Furthermore, the detailed recollections of visual awareness in this case were consistent with verified events.

So, while it wasn't possible to absolutely prove the reality or meaning of these experiences, it was not possible to discredit them. More work is clearly needed. Here's what Parnia concluded from the study:

The themes relating to the experience of death appear far broader than what has been understood so far, or what has been described as so called near-death experiences.

In some cases of cardiac arrest, memories of visual awareness compatible with so called out-of-body experiences may correspond with actual events.

A higher proportion of people may have vivid death experiences, but do not recall them due to the effects of brain injury or sedative drugs on memory circuits.

Widely used yet scientifically imprecise terms such as near-death and out-of-body experiences may not be sufficient to describe the actual experience of death. Future studies should focus on cardiac arrest, which is biologically synonymous with death, rather than ill-defined medical states sometimes referred to as 'near-death'.

The recalled experience surrounding death merits a genuine investigation without prejudice.

Rethinking Death

Contrary to perception, death is not a specific moment but a potentially reversible process that occurs after any severe illness or accident causes the heart, lungs and brain to cease functioning. If attempts are made to reverse this process, it is referred to as 'cardiac arrest'; however, if these attempts do not succeed it is called 'death'. In this study we wanted to go beyond the emotionally charged yet poorly defined term of NDEs to explore objectively what happens when we die.

The phrase "a potentially reversible process" jibes well with burgeoning definitions of death — definitions that consider factors other than a heartbeat and electrical brain activity. Cryonicists, for example, refer to "information theoretic brain death" — the notion that death does not occur until all the information in your brain that's required to resuscitate you (or reanimate you) is irrevocably destroyed.

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Less conceptually, Parnia's paper suggests that we should push the boundary as it pertains to the declaration of death in consideration of novel interventions, like cold stasis, that may bring people back in the precious moments following a cardiac arrest.